Search results for " gases"

Natural Halogen Emissions to the Atmosphere: Sources, Flux, and Environmental Impact

2022

Understanding the atmospheric geochemical cycle of both natural and anthropogenic halogens is important because of the detrimental effect halogens have on the environment, notably on tropospheric and stratospheric ozone. Oceans are the primary natural source for atmospheric Cl, F, Br, and I, but anthropogenic emissions are still important, especially for Cl. While emissions of human-made halocarbons (e.g., chlorofluorocarbons or CFCs) are expected to continue to decrease allowing progressive stratospheric ozone recovery, volcanic activity (e.g., clusters of mid-scale explosive eruptions or large-scale explosive eruptions) might disturb this recovery over the next decades. This review provid…

The modelling of the behaviour of solid inclusions in the EM induced recirculated turbulent flows of liquid metal

2014

Promocijas darbā skaitliski un eksperimentāli pētītas noslēgtas elektromagnētiski ierosinātas šķidrā metāla turbulentās plūsmas ar cietām daļiņām. Šādas plūsmas veidojas metalurģiskajās indukcijas krāsnīs. Darbā ir izveidots uz LES plūsmas aprēķina pieejas bāzēts Lagranža modelis ar paplašinātu spēku kopu inerciālo daļiņu pārneses aprakstam. Veikts eksperimentāls daļiņu koncentrācijas pētījums kvazi-stacionārā stāvoklī, izmantojot jaunu ideju: ferromagnētiskās daļiņas izmantotas kā nevadošu daļiņu fiziskais modelis šķidrajā metālā - tas ir pirmais zināmais eksperimentālais darbs cietu ieslēgumu sadalījuma analīzē elektormagnētiski ierosinātu šķidro metālu plūsmu iekšienē. Eksperiments pierā…

Unraveling the nature of universal dynamics in O(N) theories

2020

Many-body quantum systems far from equilibrium can exhibit universal scaling dynamics which defy standard classification schemes. Here, we disentangle the dominant excitations in the universal dynamics of highly occupied N-component scalar systems using unequal-time correlators. While previous equal-time studies have conjectured the infrared properties to be universal for all N, we clearly identify for the first time two fundamentally different phenomena relevant at different N. We find all N >= 3 to be indeed dominated by the same Lorentzian "large-N" peak, whereas N = 1 is characterized instead by a non-Lorentzian peak with different properties, and for N = 2, we see a mixture of two cont…

Vortex dynamics in rotating counterflow and plane Couette and Poiseuille turbulence in superfluid Helium

2008

An equation previously proposed to describe the evolution of vortex line density in rotating counterflow turbulent tangles in superfluid helium is generalized to incorporate nonvanishing barycentric velocity and velocity gradients. Our generalization is compared with an analogous approach proposed by Lipniacki, and with experimental results by Swanson et al. in rotating counterflow, and it is used to evaluate the vortex density in plane Couette and Poiseuille flows of superfluid helium.

High-spectral-resolution Fabry-Pérot interferometers overcome fundamental limitations of present volcanic gas remote sensing techniques

2023

Remote sensing (RS) of volcanic gases has become a central tool for studying volcanic activity. For instance, ultraviolet (UV) skylight spectroscopy with grating spectrographs (GS) enables SO2 (and, under favourable conditions, BrO) quantification in volcanic plumes from autonomous platforms at safe distances. These measurements can serve volcanic monitoring and they cover all stages of volcanic activity in long measurement time series, which substantially contributes to the refinement of theories on volcanic degassing. Infrared (IR) remote sensing techniques are able to measure further volcanic gases (e.g., HF, HCl, CO2, CO). However, the employed Fourier transform spectrometers (FTSs) are…

Time resolved emission at 1.3 μm of a single InAs quantum dot by using a tunable fibre Bragg grating

2013

Photoluminescence and time resolved photoluminescence from single metamorphic InAs/GaAs quantum dots (QDs) emitting at 1.3 mu m have been measured by means of a novel fibre-based characterization set-up. We demonstrate that the use of a wavelength tunable fibre Bragg grating filter increases the light collection efficiency by more than one order of magnitude as compared to a conventional grating monochromator. We identified single charged exciton and neutral biexciton transitions in the framework of a random population model. The QD recombination dynamics under pulsed excitation can be understood under the weak quantum confinement potential limit and the interaction between carriers at the …

Three-dimensional skyrmions in spin-2 Bose–Einstein condensates

2017

We introduce topologically stable three-dimensional skyrmions in the cyclic and biaxial nematic phases of a spin-2 Bose-Einstein condensate. These skyrmions exhibit exceptionally high mapping degrees resulting from the versatile symmetries of the corresponding order parameters. We show how these structures can be created in existing experimental setups and study their temporal evolution and lifetime by numerically solving the three-dimensional Gross-Pitaevskii equations for realistic parameter values. Although the biaxial nematic and cyclic phases are observed to be unstable against transition towards the ferromagnetic phase, their lifetimes are long enough for the skyrmions to be imprinted…

Superfluid weight and Berezinskii-Kosterlitz-Thouless transition temperature of twisted bilayer graphene

2019

We study superconductivity of twisted bilayer graphene with local and non-local attractive interactions. We obtain the superfluid weight and Berezinskii-Kosterlitz-Thouless (BKT) transition temperature for microscopic tight-binding and low-energy continuum models. We predict qualitative differences between local and non-local interaction schemes which could be distinguished experimentally. In the flat band limit where the pair potential exceeds the band width we show that the superfluid weight and BKT temperature are determined by multiband processes and quantum geometry of the band.

Editeur. Special Issue Strategies for Nitrous Oxide Emission Mitigation in Agrosystems". Agriculture-Basel

2022

Towards Controlled Synthesis of Water-Soluble Gold Nanoclusters : Synthesis and Analysis

2019

Water-soluble gold nanoclusters with well-defined molecular structures and stability possess particular biophysical properties making them excellent candidates for biological applications as well as for fundamental spectroscopic studies. The currently existing synthetic protocols for atomically monodisperse thiolate-protected gold nanoclusters (AuMPCs) have been widely expanded with organothiolates, yet the direct synthesis reports for water-soluble AuMPCs are still deficient. Here, we demonstrate a wet-chemistry pH-controlled synthesis of two large water-soluble nanoclusters utilizing p-mercaptobenzoic acid (pMBA), affording different sizes of plasmonic AuMPCs on the preparative scale (∼7 …