RESUMEN
In this study, the wetting and dewetting behaviors of water nanodroplets containing various molecule numbers on nanopillar-arrayed surfaces in the presence or absence of an external electric field are investigated via molecular dynamics (MD) simulations, aiming to examine whether there is a scale effect. The results show that, in the absence of an electric field, nanodroplets on coexisting Cassie/Wenzel surfaces may be in the Cassie or the Wenzel state depending on their initial states, and apparent contact angles of the Cassie or Wenzel nanodroplets increase monotonously with increasing the droplet size. Energy analysis shows that on the same coexisting Cassie/Wenzel surface, when an electric field is imposed, a small nanodroplet possesses a lower energy barrier separating the Cassie state from the Wenzel state. Therefore, the small nanodroplet is easier to collapse into the Wenzel state. Moreover, the spontaneous Wenzel-to-Cassie dewetting transition is not observed for the nanodroplets after the removal of the electric field because the Wenzel state is a globally stable energetic state. With the same pillar geometry, both the wetting transition and the dewetting transition are significantly modified for liquids with higher intrinsic contact angles. The energy barrier of the wetting transition increases for both the large and small nanodroplets, meaning that the Cassie state becomes more robust. The energy curve shows that the Wenzel state of the large nanodroplet has higher energy so that the droplet can return to the Cassie state when removing the electric field. Intriguingly, although the small Wenzel nanodroplet has lower energy in the presence of the electric field, the dewetting transition still occurs. The increased solid-liquid interfacial tension when removing the electric field is responsible for this abnormal result. The wetting and dewetting transitions follow different energy pathways, leading to a hysteresis energy loop. There exists a critical water molecule number separating the unstable/stable Wenzel configurations, above which the Cassie state is energetically favorable and the dewetting transition can occur spontaneously after removing the electric field.
RESUMEN
Sweeping deposited particles is absolutely essential in order to maintain the excellent functionality of superhydrophobic surfaces. Many methods have been proposed to sweep microparticles deposited on tips of micro/nanostructures. However, how to sweep nanoparticles trapped in cavities of superhydrophobic surfaces has remained an outstanding issue. Here, we show that harnessing the reversible wetting transition provides a feasible way to sweep such nanoparticles. Using molecular dynamics simulations, we demonstrate that the electrically induced CB-W wetting transition makes liquid intrude into a groove and wet a trapped hydrophilic nanoparticle; however, once the electric field is removed, a spontaneous W-CB dewetting transition happens, and the extruded liquid transports the hydrophilic nanoparticle to the groove top, successfully picking up the trapped hydrophilic nanoparticle. We further find that the adhesion between the nanoparticle and groove bottom wall hinders the successful pickup, and picking up such a nanoparticle requires a stronger particle hydrophilicity. With the introduction of amphiphilic Janus particles into a liquid, we exhibit that the electrically induced reversible wetting transition can also successfully pick up a trapped hydrophobic nanoparticle. By means of calculations of the potential of mean force (PMF), we reveal pathways of both the CB-W wetting transition and the W-CB dewetting transition and hence answer why and how a hydrophilic or a hydrophobic nanoparticle is picked up successfully.
RESUMEN
When droplets are placed on hydrophobic textured surfaces, different wetting states Cassie-Baxter (CB) state or Wenzel (W) state may occur depending on materials and structures of surfaces, types and sizes of droplets, thermal fluctuations, and external stimuli. The wetting transition from the CB to the W state and the opposite process have attracted a great deal of attention because of their primary importance for designing and fabricating textured surfaces. In this work, molecular dynamics (MD) simulations are employed to understand the mechanism behind the CB-to-W transition for a nanoscale water film placed on a surface decorated with a single nanogroove when an external electric field is applied. The free energy variation during the transition process is computed on the basis of the restrained MD simulations. Water intrusion into the groove is observed by simulation snapshots, which provides direct evidence for the electric field-induced CB-to-W transition. In the previous experiments, however, only a sharp reduction in the apparent contact angle is employed to judge whether the transition takes place. The free energy curves reveal that there are two energy barriers separating the CB and W states (Δ E1) as well as separating the W and CB states (Δ E2). Owing to the presence of Δ E1, although the CB state has a higher free energy than the W state, it cannot spontaneously convert to the W state. When the external energy input exceeds Δ E1, the CB-to-W transition can be triggered, otherwise the transition will stop, and the water film will return to the CB state. Moreover, it is found that the maximum of free energy always occurs after the film touches the groove bottom. Thus, the requirement that the film should touch the groove bottom is responsible for the presence of the energy barrier Δ E1. Finally, the dependence of the two energy barriers on the electric field strength, groove aspect ratio, and intrinsic contact angle of the groove is also discussed.
RESUMEN
Systemic lupus erythematosus (SLE) is a multisystem inflammatory disease of unknown etiology. Corticosteroids and immunosuppressive agents are the principal forms of treatment for this condition. While cardiovascular disease (CVD) is known to be a major cause of death in patients with SLE, there has been no improvement over the last few decades with regard to diagnosis, treatment, or prognosis. The QRISK3 algorithm is a new algorithm that includes SLE-related risk factors; this tool can predict the risk of CVD over a ten-year period. In this study, involving 180 patients, we compared the performance of the Framingham risk score, the recalibrated risk prediction SCORE, and QRISK3 for the assessment of CVD in patients with a long course of disease and low disease activity. Then, we used a more efficient algorithm, QRISK3 to identify the risk factors for CVD. This was a prospective and cross-sectional study involving 116 patients. All patients fulfilled the ACR criteria. The systemic lupus erythematosus disease activity index 2000 (SLEDAI-2K) is widely used to assess disease activity in SLE patients; patients with a SLEDAI-2K less than or equal to 4 are considered to be stable. Thus, we defined well-controlled patients as those with a SLEDAI-2K score less than or equal to 4. The dose of glucocorticoid (GC) that patients received was less or equal to 10 mg per day. We recorded and assessed a range of traditional risk factors, current treatments, comorbidities, data at the time of onset, and SLE-related evaluations. The QRISK3 score, and the relative risk (RR) that this score defined, were used to estimate the risk of CVD in patients with SLE. According to these relative risks, the patients were divided into low- (n=28), intermediate- (n=46), and high-relative risk (n=31) groups for subgroup analysis. Of the 116 patients enrolled, 105 were eligible to be assessed for the risk of CVD. By univariate analyses, the RR was significantly related with age at the time of enrolment (p<0.001), age at onset (p<0.001), resting heart rate (RHR) (p<0.001), present dose of GCs (p<0.001), present SLEDAI-2K (p=0.015), aerobic exercise (p<0.001), initial SLEDAI-2K (p<0.001), and initial dose of GCs (p=0.048). In the multiple linear regression model, the RR of CVD was significantly correlated with the initial SLEDAI-2K score (ß=2.112, p<0.001), initial dose of GCs (ß=-0.009, p=0.041), resting heart rate (ß=0.241, p=0.003) and age at onset (ß=-0.208, p=0.004). Pearson's correlation showed that RHR was significantly associated with aerobic exercise (r=-0.322, p=0.001). Subgroup analysis further identified a positive correlation between the history of nephritis, metabolic syndrome (MetS), aerobic exercise, present dose of GCs, and the RR of CVD. Patients with long-term but well-controlled SLE had a high relative risk of CVD and that this was associated with resting heart rate (P=0.003), history of lupus nephritis (P<0.001), initial SLEDAI-2K score (P<0.001), and metabolic syndrome (P=0.017). However, age at onset (P<0.001), use of hydroxychloroquine (P=0.30) and Mycophenolate mofetil (P=0.01), and the initial dose of glucocorticoid (P=0.049), were protective factors. Younger SLE patients had a significantly higher relative risk of CVD than older patients (p<0.001). QRISK3 detected more SLE patients at high risk of CVD when compared to the Framingham and recalibrate SCORE. To reduce the risk of CVD in SLE patients, measures should be taken both during the initial stages of disease and for long-term management.
RESUMEN
Anti-neutrophil cytoplasmic antibody (ANCA) associated vasculitis (AAV) is a systemic autoimmune disease characterized by leukocytoclastic inflammation of small blood vessels. Commonly detected autoantibodies include anti-protease 3 (PR3) and anti-myeloperoxidase (MPO). Although cell necrosis plays an important role in the production of autoantibodies and the pathogenesis of AAV, the correlation between their titers and disease activity remains elusive. As improved detection techniques facilitate early diagnosis, a satisfactory efficacy can be achieved in patients with mild to medium severe AAV treated with glucocorticoids and immunosuppressants. However, resistant and relapsing AAV, sometimes life-threatening, do exist in clinical practice. In-depth understanding of pathogenesis of AAV may lend novel insight into the mechanism responsible for its formation and help find effective targeted therapies for refractory patients.