Droplet impacting a superhydrophobic mesh array: Effect of liquid properties

Generation of monodisperse droplets by a large droplet impacting a mesh array is a common technique in microfluidic engineering, materials science, and drug production. Understanding the dynamic mechanism behind this is critical to controlling this process. This work uses a nonorthogonal multiple-relaxation-time lattice Boltzmann (LB) method to simulate a droplet impacting a mesh array. By varying the droplet viscosity and surface tension, a comprehensive parametric study is carried out to investigate the influence of droplet properties on the dynamic process of droplet impact, penetration, and fragmentation. The results indicate that the inertial effect dominates the spread stage of droplet impact. At later stages, the viscous drag and surface tension act to prevent the spread of the droplet, which results in different maximum spreading diameters. The penetration of the droplet through the mesh initially leads to the formation of a liquid jet, the length of which is determined by the competition between the dynamic pressure and capillary pressure. Different jet breakup lengths are observed for various Weber numbers. The maximum spreading diameter and jet breakup length are predicted by an extended model over a wide range of liquid properties, in good agreement with the LB simulation results. An analysis is also conducted from an energy perspective. It is found that the surface energy significantly decreases after the fragmentation of the high-viscosity droplet, which is caused by the merge of satellite droplets after the jet breakup

Molecular dynamics study on evaporation of metal nitrate-containing nanodroplets in flame spray pyrolysis

Flame spray pyrolysis (FSP) provides an advantageous synthetic route for LiNi1−x−yCoxMnyO2 (NCM) materials, which are one of the most practical and promising cathode materials for Li-ion batteries. However, a detailed understanding of the NCM nanoparticle formation mechanisms through FSP is lacking. To shed light on the evaporation of NCM precursor droplets in FSP, in this work, we employ classical molecular dynamics (MD) simulations to explore the dynamic evaporation process of nanodroplets composed of metal nitrates (including LiNO3, Ni(NO3)2, Co(NO3)2, and Mn(NO3)2 as solutes) and water (as solvent) from a microscopic point of view. Quantitative analysis on the evaporation process has been performed by tracking the temporal evolution of key features including the radial distribution of mass density, the radial distribution of number density of metal ions, droplet diameter, and coordination number (CN) of metal ions with oxygen atoms. Our MD simulation results show that during the evaporation of an MNO3-containing (M = Li, Ni, Co, or Mn) nanodroplet, Ni2+, Co2+, and Mn2+ will precipitate on the droplet surface, forming a solvent–core–solute–shell structure; whereas the distribution of Li+ within the evaporating LiNO3-containing droplet is more even due to the high diffusivity of Li+ compared with other metal ions. For the evaporation of a Ni(NO3)2- or Co(NO3)2-containing nanodroplet, the temporal evolution of the CN of M–OW (M = Ni or Co; OW represents O atoms from water) suggests a “free H2O” evaporation stage, during which both CN of M–OW and CN of M–ON are unchanged with time. Evaporation rate constants at various conditions are extracted by making analogy to the classical D2 law for droplet evaporation. Unlike Ni or Co, CN of Mn–OW keeps changing with time, yet the temporal evolution of the squared droplet diameter indicates the evaporation rate for a Ni(NO3)2-, Co(NO3)2-, or Mn(NO3)2-containing droplet is hardly affected by the different types of the metal ions

Three-dimensional shock-sulfur hexafluoride bubble interaction

The evolution of shock-sulfur hexafluoride (SF6) bubble interaction is investigated using a detailed three-dimensional numerical simulation. The influences of the end wall distance on the bubble evolution are analyzed by using the high-resolution simulations. The results show that vorticities mainly emerge at the interfaces of the shock wave and the SF6 bubble, and a downstream jet is formed, owing to the impingement of the high pressure in the vicinity of the downstream pole of the bubble and the induction of nearby vorticities. Besides, the big vortices of the SF6 bubble could interact with the walls in the y-direction to increase the bubble volume. When the end wall distance is shortened, a short and wide downstream jet is formed, owing to the untimely interaction of the reflected shock wave with the distorted SF6 bubble. Also, a new upstream jet emerges behind the impingement of the reflected shock wave, and there is no interaction between the distorted SF6 bubble and the wall in the y-direction until a very late time. From a quantitative point of view, the discrepancy between the bubble volume and effective bubble volume is larger in the case with a long end wall distance, which has enhanced vorticities and strengthened bubble-wall interaction. Moreover, the reflected shock wave has a dominant compression effect on the distorted SF6 bubble evolution for the two cases with different end wall distances, but for the case with a longer end wall distance, the bubble-wall interaction has a more significant influence than the influence of vorticities on the bubble volume increase. The computational results demonstrate the three-dimensional effects of shock-SF6 bubble interactions, which have not been seen in previous two-dimensional simulations

CRTC1 transcriptional coactivator is required for hepatitis B virus gene expression and replication

This journal suppl. entitled: Metabolism, Diet and Disease 2014: Cancer and metabolismConference Theme: Cancer and metabolismPoster Presentation: P31BACKGROUND: Chronic hepatitis B virus (HBV) infection occurs in over 400 million people worldwide, 15-40% of whom will terminally develop severe liver diseases including hepatocellular carcinoma. Although development of HCC is a multi-step process, high HBV DNA level is a major risk factor for disease progression. Transcription of HBV from the cccDNA template is essential for its replication and requires CREB transcription factor, a master regulator of cell metabolism. However, transcriptional coactivators that facilitate CREB-dependent activation of HBV transcription remain to be identified and characterized …published_or_final_versio

BCI-FES training system design and implementation for rehabilitation of stroke patients

Author name used in this publication: Kai-yu TongAuthor name used in this publication: Suk-tak ChanRefereed conference paper2007-2008 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe

Cerebral plasticity after subcortical stroke as revealed by cortico-muscular coherence

Author name used in this publication: Kai-Yu TongAuthor name used in this publication: Suk-Tak Chan2008-2009 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Flavonoid intake and the risk of age-related cataract in China’s Heilongjiang Province

Background/Objectives: Epidemiological evidence suggests that diets rich in flavonoids may reduce the risk of developing age-related cataract (ARC). Flavonoids are widely distributed in foods of plant origin and the objective of this study was to evaluate retrospectively the association between the intakes of the five flavonoid subclasses and the risk of ARC.  Subjects/Methods: A population-based case-control study (249 cases and 66 controls) was carried out in Heilongjiang province, which is located in the Northeast of China, and where intakes and availability of fresh vegetables and fruits can be limited. Dietary data gathered by food-frequency questionnaire (FFQ) were used to calculate flavonoid intake. Adjusted odds ratio (OR) and 95% confidence interval (CI) were estimated by logistic regression.  Results: No linear associations between risk of developing ARC and intakes of total dietary flavonoids, anthocyanidins, flavon-3-ol, flavanone, total flavones or total flavonols were found, but quercetin and isorhamnetin intake was inversely associated with ARC risk (OR 11.78, 95% CI: 1.62-85.84, P<0.05, and OR 6.99, 95% CI:1.12-43.44, P<0.05, quartile 4 vs quartile 1, respectively).  Conclusion: As quercetin is contained in many plant foods and isorhamnetin is only contained in very few foods, we concluded that higher quercetin intake may be an important dietary factor in the reduction of risk of age-related cataract

Nicotinic acetylcholine receptor expression in human airway correlates with lung function

Nicotine and its derivatives, by binding to nicotinic acetylcholine receptors (nAChRs) on bronchial epithelial cells, can regulate cellular signaling and inflammatory processes. Delineation of nAChR subtypes and their responses to nicotine stimulation in bronchial epithelium may provide information for therapeutic targeting in smoking-related inflammation in the airway. Expression of nAChR subunit genes in 60 bronchial epithelial biopsies and immunohistochemical staining for the subcellular locations of nAChR subunit expression were evaluated. Seven human bronchial epithelial cell lines (HBECs) were exposed to nicotine in vitro for their response in nAChR subunit gene expression to nicotine exposure and removal. The relative normalized amount of expression of nAChR α4, α5, and α7 and immunohistochemical staining intensity of nAChR α4, α5, and β3 expression showed significant correlation with lung function parameters. Nicotine stimulation in HBECs resulted in transient increase in the levels of nAChR α5 and α6 but more sustained increase in nAChR α7 expression. nAChR expression in bronchial epithelium was found to correlate with lung function. Nicotine exposure in HBECs resulted in both short and longer term responses in nAChR subunit gene expression. These results gave insight into the potential of targeting nAChRs for therapy in smoking-related inflammation in the airway.postprin

LKB1 tumor suppressor and salt-inducible kinases negatively regulate human T-cell leukemia virus type 1 transcription

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Requirement of CRTC1 coactivator for hepatitis B virus transcription

Transcription of hepatitis B virus (HBV) from the covalently closed circular DNA (cccDNA) template is essential for its replication. Suppressing the level and transcriptional activity of cccDNA might have anti-HBV effect. Although cellular transcription factors, such as CREB, which mediate HBV transcription, have been well described, transcriptional coactivators that facilitate this process are incompletely understood. In this study we showed that CREB-regulated transcriptional coactivator 1 (CRTC1) is required for HBV transcription and replication. The steady-state levels of CRTC1 protein were elevated in HBV-positive hepatoma cells and liver tissues. Ectopic expression of CRTC1 or its homolog CRTC2 or CRTC3 in hepatoma cells stimulated the activity of the preS2/S promoter of HBV, whereas overexpression of a dominant inactive form of CRTC1 inhibited HBV transcription. CRTC1 interacts with CREB and they are mutually required for the recruitment to the preS2/S promoter on cccDNA and for the activation of HBV transcription. Accumulation of pregenomic RNA (pgRNA) and cccDNA was observed when CRTC1 or its homologs were overexpressed, whereas the levels of pgRNA, cccDNA and secreted HBsAg were diminished when CRTC1 was compromised. In addition, HBV transactivator protein HBx stabilized CRTC1 and promoted its activity on HBV transcription. Our work reveals an essential role of CRTC1 coactivator in facilitating and supporting HBV transcription and replication.published_or_final_versio