25 Timely perception of adverse environmental changes is critical for survival. Dynamic 26 changes in gases are important cues for plants to sense environmental perturbations, such 27 as submergence. In Arabidopsis thaliana, changes in oxygen and nitric oxide (NO) control 28 the stability of ERFVII transcription factors. ERFVII proteolysis is regulated by the N-29 degron pathway and mediates adaptation to flooding-induced hypoxia. However, how 30 plants detect and transduce early submergence signals remains elusive. Here we show that 31 plants can rapidly detect submergence through passive ethylene entrapment and use this 32 signal to pre-adapt to impending hypoxia. Ethylene can enhance ERFVII stability prior to 33 hypoxia by increasing the NO-scavenger PHYTOGLOBIN1. This ethylene-mediated NO 34 depletion and consequent ERFVII accumulation pre-adapts plants to survive subsequent 35 hypoxia. Our results reveal the biological link between three gaseous signals for the 36 regulation of flooding survival and identifies novel regulatory targets for early stress 37 perception that could be pivotal for developing flood-tolerant crops. 38 39 42 cellular oxygen (O 2 ) deprivation (hypoxia) and survival strongly depends on molecular responses 43 that enhance hypoxia tolerance 2,3 . In submerged plant tissues the limited gas diffusion causes 44 passive ethylene accumulation. This rapid ethylene build-up can occur prior to the onset of 45 severe hypoxia, making it a timely and reliable signal for submergence 4,5 . In several plant 46 species, ethylene regulates adaptive responses to flooding involving morphological and 47anatomical modifications that prevent hypoxia 5 . Surprisingly, ethylene has so far not been 48 linked to metabolic responses that reduce hypoxia damage. In addition, how plants detect and 49 transduce early submergence signals to enhance survival remains elusive. 50 Here we show that plants can quickly detect submergence using passive ethylene accumulation 51 and integrate this signal to acclimate to subsequent hypoxia. This ethylene-mediated hypoxia 52 acclimation is dependent on enhanced ERFVII stability prior to hypoxia. We show that ethylene 53 limits ERFVII proteolysis under normoxic conditions by increasing the NO-scavenger 54 3 PHYTOGLOBIN1. Our results reveal a molecular mechanism that plants use to integrate early 55 stress signals to pre-adapt to forthcoming severe stress. 57 Results 58Early ethylene signalling enhances hypoxia acclimation 59 To unravel the spatial and temporal dynamics of ethylene signalling upon plant submergence, we 60 monitored the nuclear accumulation of ETHYLENE INSENSITIVE 3 (EIN3) 6-9 , an essential 61 transcription factor for mediating ethylene responses. We show, through an increase in EIN3- 62GFP fluorescence signal, that ethylene is rapidly perceived (within 1-2 h) in Arabidopsis 63 thaliana (hereafter Arabidopsis) root tips upon submergence (Supplementary Figure 1a-c). An 64 ethylene or submergence pre-treatment of only 4 hours was sufficient to increase root m...

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The effect that the solid inlet design has on the continuous drying of sand in a conical spouted bed has been studied. Five designs have been tried, four of which are feeding the solid from the top and the fifth one into the spout. Three internal devices have been tested, a draft tube, fountain confiner, and new solid driver, to drive the solid to the fountain periphery. A hydrodynamic study has been conducted using beds of dry particles to delimit stable systems, which have been used for the drying of sands of two different size ranges. The more efficient operation is attained by distributing the bed onto the annulus or by feeding the solid into the downward section in the fountain periphery. These configurations allow attaining high efficiencies, with the product moisture content being well below specifications and the bed temperature being close to the adiabatic saturation temperature.

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