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Coalescence-induced droplet jumping on superhydrophobic surfaces has been observed at microscale and even nanoscale. The enhancement in jumping velocity of coalescing droplets is crucial for condensation heat transfer enhancement, antiicing, self-cleaning, and so forth. However, the research on how to acquire a higher jumping velocity is really very limited. In this paper, we use molecular dynamics simulations to study the coalescence-induced jumping of two equally sized nanodroplets on chemically heterogeneous surfaces composed of alternating stripes with different hydrophobicity. We show that the jumping velocity is closely related to the stripe width and wettability contrast, and it can even exceed that on an ideal superhydrophobic surface with 180 [degrees] contact angle when the striped surfaces are properly designed. We also demonstrate that there is always an optimal stripe width yielding the maximum jumping velocity, whereas its value is independent of the wettability contrast. We reveal that the dominant factor to determine the jumping velocity is the apparent contact angle of equilibrated droplets over heterogeneous surfaces for small stripe widths; it changes to the time of liquid bridges impacting surfaces for moderate stripe widths and to the contact area between equilibrated droplets and relatively hydrophobic stripes for large stripe widths. We believe the present simulations can provide useful guidance to design self-jumping superhydrophobic surfaces. Key words: mixed-wettability, superhydrophobic surfaces, coalescence, jumping velocity, molecular dynamics simulations. Les sauts de gouttelettes induits par coalescence sur une surface super-hydrophobe s'observent aux echelles micro et nano. L'accroissement de la vitesse de saut des gouttelettes se fusionnant est cruciale pour l'augmentation du transfert de chaleur par condensation, pour l'antigivrage, l'auto-nettoyage, etc. Cependant, il n'y a que tres peu de recherche sur le moyen d'augmenter la vitesse de saut. Nous utilisons ici des simulations de dynamique moleculaire pour etudier le sautillement, induit par leur fusion, de deux nano-gouttelettes de meme grosseur sur des surfaces chimiquement heterogenes composees de bandes alternees de differente hydrophobicite. Nous montrons que la vitesse de saut est etroitement reliee a la largeur de ces bandes et du contraste de mouillabilite et qu'elle peut meme exceder celle sur une surface superhydrophobe continue ideale avec un angle de surface de 180 [degrees], a condition que les surfaces striees soient concues de facon appropriees. Nous annoncons aussi qu'il y a une largeur de bande optimale produisant une vitesse de saut maximale, et que sa valeur est independante du contraste de mouillabilite. Nous revelons que, sur les surfaces heterogenes avec des bandes de petites largeurs, le facteur dominant pour determiner la vitesse de saut est l'angle de contact apparent des gouttelettes en equilibre, mais pour des bandes de largeur moyenne, ce facteur dominant devient le temps du pont liquide impactant la surface, alors que pour des bandes de grande largeur, il devient la surface de contact entre les gouttelettes equilibrees et les bandes relativement hydrophobes. Nous croyons que les resultats de ces simulations fourniront des guides utiles dans la conception des surfaces super-hydrophobes auto-sautillantes. [Traduit par la Redaction] Mots-cles : mouillabilite mixte, super-hydrophobe, coalescence/fusion, vitesse de saut, simulations de dynamique moleculaire., 1. Introduction Coalescence-induced droplet jumping on superhydrophobic surfaces was first discovered by Boreyko and Chen in 2009 [1]. Over the past decade, this phenomenon has received more and more attention [...]

Exposure of dark-grown etiolated seedlings to light triggers the transition from skotomorphogenesis/etiolation to photomorphogenesis/de-etiolation. In the life cycle of plants, de-etiolation is essential for seedling development and plant survival. The mobilization of soluble sugars (glucose [Glc], sucrose, and fructose) derived from stored carbohydrates and lipids to target organs, including cotyledons, hypocotyls, and radicles, underpins de-etiolation. Therefore, dynamic carbohydrate biochemistry is a key feature of this phase transition. However, the molecular mechanisms coordinating carbohydrate status with the cellular machinery orchestrating de-etiolation remain largely opaque. Here, we show that the Glc sensor HEXOKINASE 1 (HXK1) interacts with GROWTH REGULATOR FACTOR5 (GRF5), a transcriptional activator and key plant growth regulator, in Arabidopsis (Arabidopsis thaliana). Subsequently, GRF5 directly binds to the promoter of phytochrome A (phyA), encoding a far-red light (FR) sensor/cotyledon greening inhibitor. We demonstrate that the status of Glc within dark-grown etiolated cotyledons determines the de-etiolation of seedlings when exposed to light irradiation by the HXK1–GRF5–phyA molecular module. Thus, following seed germination, accumulating Glc within dark-grown etiolated cotyledons stimulates a HXK1-dependent increase of GRF5 and an associated decrease of phyA, triggering the perception, amplification, and relay of HXK1-dependent Glc signaling, thereby facilitating the de-etiolation of seedlings following light irradiation. Our findings, therefore, establish how cotyledon carbohydrate signaling under subterranean darkness is sensed, amplified, and relayed, determining the phase transition from skotomorphogenesis to photomorphogenesis on exposure to light irradiation. This study reveals how sugar signaling under subterranean darkness is sensed, amplified, and relayed to determine skototophotomorphogenesis upon exposure to light irradiation. [ABSTRACT FROM AUTHOR]

A novel method to fabricate flexible free-standing electrodes with textile structure for lithium-ion batteries was provided by applying extrusion-based three-dimensional (3D) printing technology. Meanwhile, highly concentrated poly(vinylidene fluoride) (PVDF) is used as viscosity modifier, carbon nanotube (CNT) as conducting additive, and lithium iron phosphate (LFP) or lithium titanium oxide (LTO) as cathode or anode active materials respectively to develop printable inks with obvious shear-thinning behavior, and with the apparent viscosity and storage modulus platform value of over 105Pa·s, which is beneficial to the printability and enable complex 3D structures solidification. The electrochemical test shows that both printed electrodes have similar charge and discharge specific capacities under current density of 50mA·g-1. To explore the feasibility of the printed electrodes, a pouch cell with as-printed LFP and LTO electrode as cathode and anode respectively is assembled. The pouch cell without deformation delivers discharge specific capacities of approximately 108mAh·g-1, and there is a tiny increase in discharge specific capacities of around 111mAh·g-1 for bended pouch cell.

This study investigates the heat transfer enhancement by electrohydrodynamic (EHD) in a rectangular channel with various geometric and operational parameters in a wide NEHD range of 0.4–5. Here, NEHD is a dimensionless number, describing the ratio of electrostatic, inertial, and viscous forces. Two working regimes in EHD are identified: inertial and electrostatic regimes. The results show that the barrier effect exists only in the inertial regime; however, the interference effect occurs in the electrostatic regime. The barrier effect relies heavily on NEHD rather than the dimensionless distance between electrodes l* and the dimensionless channel width H* because the thermal boundary layer cannot be disturbed sufficiently by a small electrostatic force; however, the interference effect depends on l* and H* rather than NEHD due to the stagnant area initiated only by a strong interaction between adjacent emitting electrodes. A new effect, the "blocking effect," is found in the electrostatic regime. The mechanism of the blocking effect is different from that of the barrier and interference effects. The blocking effect is initiated by a giant vortex, which "blocks" the airflow flowing toward the downstream channel. The average Nusselt number of channels can be reduced by at least 8%, 13%, and 5% for the barrier, interference, and blocking effects, respectively. A working spectrum of EHD-induced heat transfer enhancement in a rectangular channel is provided under NEHD and channel area coupling conditions. We believe the spectrum can help in designing EHD-induced heat transfer enhancement because it provides theoretical guidance for avoiding the three effects. [ABSTRACT FROM AUTHOR]