Double Droplets Impact an Inclined Superhydrophobic Surface.

The rebound dynamics of double droplets impacting an inclined superhydrophobic surface decorated with macro-ridges are investigated via lattice Boltzmann method (LBM) simulations. Four rebound regions are identified, that is, the no-coalescence-rebound (NCR), the partial-coalescence-rebound of the middle part bounces first (PCR-M), and the side part bounces first (PCR-S), as well as the complete-coalescence-rebound (CCR). The occurrence of the rebound regions strongly depends on the droplet arrangement, the center-to-center distance of the droplets, and the Weber number. Furthermore, the contact time is closely related to the rebound regions. The PCR-M region can significantly reduce the contact time because the energy dissipation in this region may decrease which can promote the rebound dynamic. Intriguingly, the contact time is also affected by the droplet arrangement; i.e., droplets arranged parallel to the ridge dramatically shorten the contact time since this arrangement increases the asymmetry of the liquid film. Therefore, for multidrop impact, the contact time can be effectively manipulated by changing the rebound region and the droplet arrangement. This work focuses on elucidating the wetting behaviors, rebound regions, and contact time of the multiple-droplet impacting an inclined superhydrophobic surface decorated with macro-ridges.

Bouncing Dynamics of Drops' Successive Off-Center Impact.

Bouncing dynamics of a trailing drop off-center impacting a leading drop with varying time intervals and Weber numbers are investigated experimentally. Whether the trailing drop impacts during the spreading or receding process of the leading drop is determined by the time interval. For a short time interval of 0.15 ≤ Δt* ≤ 0.66, the trailing drop impacts during the spreading of the leading drop, and the drops completely coalesce and rebound; for a large time interval of 0.66 < Δt* ≤ 2.21, the trailing drop impacts during the receding process, and the drops partially coalesce and rebound. Whether the trailing drop directly impacts the surface or the liquid film of the leading drop is determined by the Weber number. The trailing drop impacts the surface directly at moderate Weber numbers of 16.22 ≤ We ≤ 45.42, while it impacts the liquid film at large Weber numbers of 45.42 < We ≤ 64.88. Intriguingly, when the trailing drop impacts the surface directly or the receding liquid film, the contact time increases linearly with the time interval but independent of the Weber number; when the trailing drop impacts the spreading liquid film, the contact time suddenly increases, showing that the force of the liquid film of the leading drop inhibits the receding of the trailing drop. Finally, a theoretical model of the contact time for the drops is established, which is suitable for different impact scenarios of the successive off-center impact. This study provides a quantitative relationship to calculate the contact time of drops successively impacting a superhydrophobic surface, facilitating the design of anti-icing surfaces.

Effect of Asymmetry on the Contact Time of Droplet Impact on Superhydrophobic Cylindrical Surfaces.

Reducing the contact time during the droplet impact on the surface is crucial for anti-icing, self-cleaning, and heat transfer optimization applications. This study aims to minimize the contact time by modifying the surface curvature to create an asymmetric impact process. Our experiments showed that the increase in Weber numbers (We) and the decrease in the ratio of surface diameter to droplet diameter (D*) intensify the asymmetry of the impact process, yielding four distinct rebound modes. Low asymmetry observes the liquid retract toward the central point (Rebound Modes 1 and 2), whereas high asymmetry yields a wing-like rebound (Rebound Modes 3 and 4). In Rebound Mode 1, increased asymmetry would lead to more extended contact due to the prolonged waiting period. Conversely, the reduction in contact time in Rebound Mode 2 occurs due to increased asymmetry with no waiting period. For Rebound Modes 3 and 4, the retraction time could be divided into three stages, generated by two liquid detachment modes from the surface. Analysis reveals that an increased asymmetry would reduce the retraction time during the first stage but prolong it during the third stage, with no significant effects on the second. Four correlations, each pertaining to a distinct impact mode, are proposed based on these analyses to describe the contact time concerning We and D* for droplets impacting a superhydrophobic cylindrical surface.

Theoretical and Three-Dimensional Molecular Dynamics Study of Droplet Wettability and Mobility on Lubricant-Infused Porous Surfaces.

Profiting from their slippery nature, lubricant-infused porous surfaces endow with droplets excellent mobility and consequently promise remarkable heat transfer improvement for dropwise condensation. To be a four-phase wetting system, the droplet wettability configurations and the corresponding dynamic characteristics on lubricant-infused porous surfaces are closely related to many factors, such as multiple interfacial interactions, surface features, and lubricant thickness, which keeps a long-standing challenge to promulgate the underlying physics. In this work, thermodynamically theoretical analysis and three-dimensional molecular dynamics simulations with the coarse-grained water and hexane models are carried out to explore droplet wettability and mobility on lubricant-infused porous surfaces. Combined with accessible theoretical criteria, phase diagrams of droplet configurations are constructed with a comprehensive consideration of interfacial interactions, surface structures, and lubricant thickness. Subsequently, droplet sliding and coalescence dynamics are quantitatively defined under different configurations. Finally, in terms of the promotion of dropwise condensation, a non-cloaking configuration with the encapsulated state underneath the droplet is recommended to achieve high droplet mobility owing to the low viscous drag of the lubricant and the eliminated pinning effect of the contact line. On the basis of the low oil-water and water-solid interactions, a stable lubricant layer with a relatively low thickness is suggested to construct slippery surfaces.

Impact Dynamics of a Single Droplet on Hydrophobic Cylinders: A Lattice Boltzmann Study.

This study numerically investigates the effects of the Weber number (We) and cylinder-to-droplet radius ratio (R*) on the impact dynamics of a low-viscosity droplet on a hydrophobic cylinder by the lattice Boltzmann method. The intrinsic contact angle of the surface is chosen as θ0 = 122°± 2°, which ensures a representative hydrophobicity. The regime diagram of the impact dynamics in the parameter space of We versus R* is established with categories of split and nonsplit regimes. The droplet would split during impact as α = We/R* exceeds a critical value. In the nonsplit regime, the droplet bounces off the cylinder at most Weber numbers unless the impact velocity is minuscule (We < 2). The contact time of the droplet on the cylinder surface decreases with increasing R* or decreasing We, indicating bouncing is facilitated under such conditions. This can be explained by the suppressed adhesion dissipation between the droplet and surface due to a reduction in the contact area. In the split regime, sufficient kinetic energy inside the impacting droplet determines whether the whole droplet could detach from the surface. With a small cylinder (R* < 0.83) and large We (>25), the adhesion effect is weakened for the side fragments because of the small contact area, and it facilitates the dripping of fragments. For other conditions, the detachment, especially for the tiny droplet on the cylinder top, only occurs if the deformation is prominent at We > 35. Moreover, the spreading dynamics of the impacting droplet are also highlighted in this work.

Rebound Behaviors of Multiple Droplets Simultaneously Impacting a Superhydrophobic Surface.

The rebound behaviors of multiple droplets simultaneously impacting a superhydrophobic surface were investigated via lattice Boltzmann method (LBM) simulations. Three rebound regions were identified, i.e., an edge-dominating region, a center-dominating region, and an independent rebound region. The occurrence of the rebound regions strongly depends on the droplet spacing and the associated Weber and Reynolds numbers. Three new rebound morphologies, i.e., a pin-shaped morphology, a downward comb-shaped morphology, and an upward comb-shaped morphology, were presented. Intriguingly, in the edge-dominating region, the central droplets experience a secondary wetting process to significantly prolong the contact time. However, in the center-dominating region, the contact time is dramatically shortened because of the strong interactions generated by the central droplets and the central ridges. These findings provide useful information for practical applications such as self-cleaning, anticorrosion, anti-icing, and so forth.

Universal Model for the Maximum Spreading Factor of Impacting Nanodroplets: From Hydrophilic to Hydrophobic Surfaces.

Using molecular dynamics (MD) simulations, we investigate impact behaviors of water nanodroplets on hydrophilic to hydrophobic surfaces with static contact angles ranging from 21 to 148° in a wide Weber number range of 15-90, aiming to understand how the surface wettability influences the maximum spreading factor of nanodroplets. We show that the existing macroscale and nanoscale models cannot capture the influence of surface wettability on the maximum spreading factor. We demonstrate that the failure is attributed to the rough estimation of the spreading velocity during the spreading stage, which is assumed to be a constant value in these models. We show that the spreading velocity strongly depends on both the surface wettability and the Weber number. After scaling with the impact velocity, we obtain a universal function of the spreading velocity with respect to the static contact angle and the Weber number. We employ this function to modify the expression of viscous dissipation and develop a new model of the maximum spreading factor. We verify that the model is in excellent agreement with the MD simulations regardless of hydrophilic and hydrophobic surfaces, with the mean relative deviation ranging from 0.88 to 4.75%. We also provide evidence to support the fact that incorporating the influence of surface wettability by modifying viscous dissipation is more reasonable than by modifying surface energy for nanodroplet impact.

How to select ionic liquids as extracting agents systematically: a special case study for extractive denitrification processes.

Extractive denitrification (EDN) of shale oil using ionic liquids (ILs) as the extracting agent has good industrial prospects. In such processes, ILs with higher selectivity to N-compounds and lower solubility in shale oil are desired to improve the EDN efficiency, and reduce the loss of ILs and the contamination of shale oil. In the present study, we employed COSMO-RS to calculate the selectivity of 70 ILs to the typical N-compounds (pyridine, quinoline and indole). The influence of the IL structural characteristics, composition of shale oil and properties of N-compounds are investigated from a micro-level view with the σ-surface and σ-profile. The selectivity strongly depends on anionic species and it is greatly influenced by hydrogen bonding (HB) and π-π interaction between N-compounds and ILs. ILs composed of [H2PO4]- and [MeSO3]- with larger HB donor energy show higher selectivity to the basic N-compounds, while ILs composed of [Ac]- with larger π-electron cloud density show higher selectivity to the non-basic N-compounds. Anions with stronger polarity have lower solubility in shale oil. Moreover, experimental determinations of EDN indicated that [C4py][H2PO4]/[C4mim][H2PO4] and [C2mim][Ac]/[C2py][Ac] have good EDN performance for quinoline/pyridine with efficiency of 100% and for indole with efficiency of 91%, respectively. This work presents a theoretical basis to design and select ILs having higher selectivity for N-compounds and lower solubility in shale oil for use in denitrification.

Grape seed procyanidin B2 promotes the autophagy and apoptosis in colorectal cancer cells via regulating PI3K/Akt signaling pathway.

Aim: Colorectal cancer (CRC) is a major malignancy in China, which is the critical risk of people health. Many natural herbs extracts have been found to exhibit good therapeutic effect on CRC. Our previous study found that grape seed procyanidins B2 (PB2) would induce CRC cell death. However, the molecular mechanism underlying its anti-tumor effect on CRC remains unclear. Thereby, this study aimed to investigate the anti-tumor mechanism of PB2 on CRC. Methods: CCK-8, western blotting, flow cytometry, qRT-PCR and animal study were used in the current study. Results: The in vitro and in vivo data demonstrated that PB2 could promote the apoptosis of CRC cells in a dose-dependent manner, which was significantly reversed by caspase 3 inhibitor. Meanwhile, PB2 dose-dependently induced autophagy in CRC cells, which was markedly attenuated by autophagy inhibitor 3-MA. In addition, PB2 dose-dependently inhibited the expressions of p-PI3K, p-Akt and p-mTOR in the cells. Conclusion: PB2 dose-dependently induced apoptosis and autophagy in CRC cells via downregulation of PI3K/Akt pathway. This study provided the experimental basis for further development of PB2 as a new effective anticancer drug for the patients with CRC.

Atractylenolide II reverses the influence of lncRNA XIST/miR-30a-5p/ROR1 axis on chemo-resistance of colorectal cancer cells.

This investigation was conducted to elucidate whether atractylenolide II could reverse the role of lncRNA XIST/miR-30a-5p/ROR1 axis in modulating chemosensitivity of colorectal cancer cells. We totally collected 294 pairs of colorectal cancer tissues and adjacent normal tissues and also purchased colorectal cancer cell lines and human embryonic kidney cell line. 5-fluorouracil, cisplatin, mitomycin and adriamycin were designated as the chemotherapies for colorectal cell lines, and atractylenolides were arranged as the Chinese drug. The expressions of XIST, miR-30a-5p and ROR1 were quantified with aid of qRT-PCR or Western blot, and luciferase reporter gene assay was implemented to determine the relationships among XIST, miR-30a-5p and ROR1. Our results demonstrated that XIST and ROR1 expressions were dramatically up-regulated, yet miR-30a-5p expression was down-regulated within colorectal cancer tissues (P < 0.05). The overexpressed XIST and ROR1, as well as under-expressed miR-30a-5p, were inclined to promote viability and proliferation of colorectal cells under the influence of chemo drugs (P < 0.05). In addition, XIST could directly target miR-30a-5p, and ROR1 acted as the targeted molecule of miR-30a-5p. Interestingly, atractylenolides not only switched the expressions of XIST, miR-30a-5p and ROR1 within colorectal cancer cells but also significantly intensified the chemosensitivity of colorectal cancer cells (P < 0.05). Finally, atractylenolide II was discovered to slow down the viability and proliferation of colorectal cancer cells (P < 0.05). In conclusion, the XIST/miR-30a-5p/ROR1 axis could be deemed as pivotal markers underlying colorectal cancer, and administration of atractylenolide II might improve the chemotherapeutic efficacy for colorectal cancer.

Inhibition of CCL19 benefits non­alcoholic fatty liver disease by inhibiting TLR4/NF­κB­p65 signaling.

Non­alcoholic fatty liver disease (NAFLD), which affects approximately one­third of the general population, has become a global health problem. Thus, more effective treatments for NAFLD are urgently required. In the present study, high levels of C­C motif ligand 19 (CCL19), signaling pathways such as Toll­like receptor 4 (TLR4)/nuclear factor­κB (NF­κB), and proinflammatory factors including interleukin­6 (IL­6) and tumor necrosis factor­α (TNF­α) were detected in NAFLD patients, thereby indicating that there may be an association between CCL19 and these factors in NAFLD progression. Using a high­fat diet (HFD), the present study generated a Sprague­Dawley rat model of NAFLD, which displayed dyslipidemia with increased levels of plasma aspartate aminotransferase, alanine aminotransferase, total cholesterol and triglyceride. Dyslipidemia, liver histopathology and gene expression analyses indicated that the NAFLD model was successfully induced by HFD, and metformin and berberine (BBR) were effective treatments for NAFLD. HFD­induced CCL19 levels and associated factors were markedly reduced by the two drug treatments. In addition, metformin or BBR alone significantly promoted adenosine monophosphate­activated protein kinase (AMPK) phosphorylation, which was inhibited by HFD. These results demonstrated that metformin and BBR could improve NAFLD, which may be via the activation of AMPK signaling, and the high expression of CCL19 in NAFLD was significantly reduced by metformin and BBR. It could be inferred that inhibition of CCL19 may be an effective treatment for NAFLD.

Radix Cyathula officinalis Kuan inhibits arterial remodeling in spontaneously hypertensive rats.

There is still no resolution for arterial remodeling related with hypertension, though hypertension treatment has access to a number of pharmacological agents. The present study aimed at investigating the prevention of Cyathula officinalis Kuan's roots (C. officinalis Kuan) against in arterial remodeling in vitro. Spontaneously hypertensive rats (SHRs) were intragastrically administered 3, 6 or 12 g/kg C. officinalis Kuan or normal saline or enalapril (2.5 mg/kg) once a day for 8 weeks. Hematoxylin and eosin were used to measure blood pressure and stain carotid and arota. The serum concentration of nitric oxide (NO) was measured by NO assay kit (nitrate reductase method). The endothelin-1 transcriptional level, endothelial NO synthase of endothelium as well as angiotensin II receptor type 1 (AT1R) of aorta and carotid was tested by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and the protein level in aorta was also measured by western blotting. The blood pressure in SHR+enalapril, SHR+3 g/kg, SHR+6 g/kg and SHR+12 g/kg C. officinalis Kuan groups was significantly decreased at 4, 6 and 8 weeks post-treatment compared with SHR group. Different doses of C. officinalis Kuan and enalapril treatment showed aortic wall thinness and strengthened NO serum level, but made no impact on the transcriptional level of AT1R in aorta or endothelial NO synthase in carotid. It is suggested by such results that therapy by C. officinalis Kuan is able to fight against arterial remodeling, thus may provide a new means to treat arterial remodeling caused by hypertension.

[Preliminary exploration on effect of qilian decoction in intervention treatment of diabetes mellitus type 2 with insulin resistance and its influence on related inflammatory cytokines].

OBJECTIVE: To observe the synergistic effect of Qilian decoction (QLD) with corresponding hypoglycemic agents on insulin sensitivity in patients with diabetes mellitus type 2 and its influence on related inflammatory cytokines. METHODS: Sixty-two patients with diabetes mellitus type 2 were selected and randomly divided into two groups, they were treated with hypoglycemic agent in routine, and QLD was given orally, one dose taken in twice a day. Parameters as fasting blood glucose, insulin, peptide C, tumor necrosis factor-alpha (TNF-alpha), C-reactive protein (CRP), interleukin 6 (IL-6) were measured before and after treatment, and insulin sensitive index (ISI) was also calculated. RESULTS: The level of fasting blood glucose lowered after treatment in both groups (P<0.01); levels of fasting insulin, peptide C, ISI, TNF-alpha, IL-6 and CRP significantly lowered after treatment (P<0.05 or P<0.01), and the effect was better than that in the control group (P<0.05 or P<0.01). CONCLUSION: QLD could improve the insulin resistance and lower the levels of related inflammatory cytokines.