No abstract

No abstract

Elasto-inertial focusing in viscoelastic fluids has attracted increasing interest in recent years due to its potential applications in particle counting and sorting. However, current investigations of the elasto-inertial focusing mechanisms have mainly been focused on simple straight channels with little attention being paid to curved channels. Herein, we experimentally explore the elasto-inertial focusing behaviors of particles in spiral microfluidic channels over a wide range of flow rates, channel aspect ratios and channel radii. As compared with those observed in inertial microfluidics without viscoelasticity, the particle focusing pattern in our spiral elasto-inertial microfluidic system appears in a more interesting manner due to the complex coupling of elasticity, inertia and Dean flow effects. On the basis of the obtained data, the underlying mechanics and force competition behind the focusing behaviors are analyzed. In addition, for the first time, we propose a six-stage process model illustrating the particle focusing process in Dean-coupled elasto-inertial flows with increasing flow rate. It is interesting to find that the Dean drag force makes a significant contribution to particle focusing only at high flow rates and finally shifts the particle focusing positions into the outer channel region. Through carefully balancing the forces acting on particles, single-line 3D focusing can also be achieved at a throughput level of ∼100 μl min(-1), which is much higher than those in most existing studies. We envision that this improved understanding of the particle focusing mechanisms would provide helpful insights into the design and operation of spiral elasto-inertial microfluidic systems.

BACKGROUND: Preeclampsia is one of the leading causes of maternal and perinatal morbidity and is characterized by hypertension, inflammation, and placental dysfunction. Gut microbiota plays key roles in inflammation and hypertension. However, its roles and mechanisms in preeclampsia have not been fully elucidated. METHODS: 16S rRNA gene sequencing and targeted metabolomics were conducted on stool samples from 92 preeclamptic patients and 86 normal late-pregnant women. Then, fecal microbiota transplantation and in vitro and in vivo functional experiments were performed to explore the roles and mechanisms of gut microbiota in preeclampsia development. RESULTS: We revealed the gut microbiota dysbiosis in preeclamptic patients, including significant reductions in short-chain fatty acid-producing bacteria and short-chain fatty acids. The gut microbiota of preeclamptic patients significantly exacerbated pathologies and symptoms of preeclamptic rats, whereas the gut microbiota of healthy pregnant women had significant protective effects. Akkermansia muciniphila, propionate, or butyrate significantly alleviated the symptoms of preeclamptic rats. Mechanistically, they significantly promoted autophagy and M2 polarization of macrophages in placental bed, thereby suppressing inflammation. Propionate also significantly promoted trophoblast invasion, thereby improved spiral arterial remodeling. Additionally, we identified a marker set consisting of Akkermansia , Oscillibacter, and short-chain fatty acids that could accurately diagnose preeclampsia. CONCLUSIONS: Our study revealed that gut microbiota dysbiosis is an important etiology of preeclampsia. Gut microbiota and their active metabolites have great potential for the treatment and diagnosis of preeclampsia. Our findings enrich the gut–placenta axis theory and contribute to the development of microecological products for preeclampsia.

No abstract