169 research outputs found
Duurzame energie: stroomt het? : belemmeringen in wet- en regelgeving en vergunningsverlening bij de implementatie van duurzame energiesystemen in de glastuinbouw
Om de implementatie van duurzame energiesystemen in de glastuinbouw te bevorderen, is het belangrijk dat zoveel mogelijk wordt voorkomen dat glastuinbouwondernemers belemmeringen ondervinden in wet- en regelgeving of vergunningverlening als ze willen omschakelen naar dergelijke energiesystemen. Andere belangen - zoals die van omwonenden, andere ondernemers, of natuur en/of drinkwater gebieden - mogen echter ook niet worden geschaad. Dit onderzoek speelt zich af in dit krachtenveld. Belemmeringen in wet- en regelgeving en vergunningverlening bij de implementatie van duurzame energiesystemen, achtergronden daarvan en oplossingsrichtingen staan centraal
An investigation of CO2 splitting using nanosecond pulsed corona discharge: effect of argon addition on CO2 conversion and energy efficiency
The plasma chemical splitting of carbon dioxide (CO2) to produce carbon monoxide (CO) in a
pulsed corona discharge was investigated from both an experimental and a numerical standpoint.
High voltage nanosecond pulses were applied to a stream of pure CO2 and its mixture with argon,
and the gaseous products were identified using Fourier transform infrared spectroscopy. Due to the
shape of pulses, the process of CO2 splitting was found to proceed in two phases. The first phase is
dominated by ionization, which generates a high electron density. Then, during the second phase,
direct electron impact dissociation of CO2 contributes to a large portion of CO production.
Conversion and energy efficiency were calculated for the tested conditions. The conversions
achieved are comparable to those obtained using other high pressure non-thermal discharges, such as
dielectric barrier discharge. However, the energy efficiencies were considerably higher, which are
favorable to industrial applications that require atmospheric conditions and elevated gas flow rates
Energy distribution of ions and fast neutrals in microdischarges for display technology
Spatial coupling of particle and fluid models for streamers: where nonlocality matters
Particle models for streamer ionization fronts contain correct electron
energy distributions, runaway effects and single electron statistics.
Conventional fluid models are computationally much more efficient for large
particle numbers, but create too low ionization densities in high fields. To
combine their respective advantages, we here show how to couple both models in
space. We confirm that the discrepancies between particle and fluid fronts
arise from the steep electron density gradients in the leading edge of the
fronts. We find the optimal position for the interface between models that
minimizes computational effort and reproduces the results of a pure particle
model.Comment: 4 pages, 5 figure
Probing background ionization: Positive streamers with varying pulse repetition rate and with a radioactive admixture
Positive streamers need a source of free electrons ahead of them to
propagate. A streamer can supply these electrons by itself through
photo-ionization, or the electrons can be present due to external background
ionization. Here we investigate the effects of background ionization on
streamer propagation and morphology by changing the gas composition and the
repetition rate of the voltage pulses, and by adding a small amount of
radioactive Krypton 85.
We find that the general morphology of a positive streamer discharge in high
purity nitrogen depends on background ionization: at lower background
ionization levels the streamers branch more and have a more feather-like
appearance. This is observed both when varying the repetition rate and when
adding Krypton 85, though side branches are longer with the radioactive
admixture. But velocities and minimal diameters of streamers are virtually
independent of the background ionization level. In air, the inception cloud
breaks up into streamers at a smaller radius when the repetition rate and
therefore the background ionization level is higher. When measuring the effects
of the pulse repetition rate and of the radioactive admixture on the discharge
morphology, we found that our estimates of background ionization levels are
consistent with these observations; this gives confidence in the estimates.
Streamer channels generally do not follow the paths of previous discharge
channels for repetition rates of up to 10 Hz. We estimate the effect of
recombination and diffusion of ions and free electrons from the previous
discharge and conclude that the old trail has largely disappeared at the moment
of the next voltage pulse; therefore the next streamers indeed cannot follow
the old trail.Comment: 30 pages, 13 figure
Dielectric barrier discharges used for the conversion of greenhouse gases: modeling the plasma chemistry by fluid simulations
Modelling acquired resistance to DOT1L inhibition exhibits the adaptive potential of KMT2A-rearranged acute lymphoblastic leukemia
In KMT2A-rearranged acute lymphoblastic leukemia (ALL), an aggressive malignancy, oncogenic KMT2A-fusion proteins inappropriately recruit DOT1L to promote leukemogenesis, highlighting DOT1L as an attractive therapeutic target. Unfortunately, treatment with the first-in-class DOT1L inhibitor pinometostat eventually leads to non-responsiveness. To understand this we established acquired pinometostat resistance in pediatric KMT2A::AFF1+ B-ALL cells. Interestingly, these cells became mostly independent of DOT1L-mediated H3K79 methylation, but still relied on the physical presence of DOT1L, HOXA9 and the KMT2A::AFF1 fusion. Moreover, these cells selectively lost the epigenetic regulation and expression of various KMT2A-fusion target genes such as PROM1/CD133, while other KMT2A::AFF1 target genes, including HOXA9 and CDK6 remained unaffected. Concomitantly, these pinometostat-resistant cells showed upregulation of several myeloid-associated genes, including CD33 and LILRB4/CD85k. Taken together, this model comprehensively shows the adaptive potential of KMT2A-rearranged ALL cells upon losing dependency on one of its main oncogenic properties
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